Dynamo-electric machine.



A.; 3. mm1 DYNAM ELECTRIC MACHINE A PPLIOATVION TILBD NOV. 30, 1906.

899,447.. Patented Sept. 1908.

'UNTED STATES le PU ALLA-N B. FlELD, OF NORWOOD7 OHIO, ASSIGNOR TO ALLES CHALMERS COMPANY, A CORPO- RATION OF NEW JERSEY, AND THE BULLOOK ELECTRIC MANUFACTURING COMPANY, A

CORPORATION OF OHIO.

Specification o' Letters Patent.

Patented Sept. 22, 1908.

Applcatiim filed November 30, 1908. Serial No. 345,602.

To all whom it may concern:

Be it known that l, ALLAN B. Frisian, citizen of the United States, residing at Norwood, in the county of Hamilton and State oi Ohio, have invented certain new and use'- lul Improvements in Dynamodlectric Machines, of which the following is a-full, clear, and exact specification.

My invention yrelates to dynamo-electric machines and particularly to anti-hunting or damping devices or to means for preventing irregularity of movement or hunting of such machines as alternating current genera-` tors, synchronous motors, rotary converters,

etc.

The obj ect of my invention is to provide an anti-hunting device which is very eitective in ope-ration, simplel in construction' and so located as not to detract from the appear-- anceol the machine or to add n'iaterially to its Weight.

My invention consists in certain novel details of construction and combinations of ele ments described in the specification and set forth in the appended claims.

The anti-hunting device may be applied to stationary or rotary members. In this particular case it is shown in connection with rotary field poles.

For a'hetter understanding oi ymy invention reference is had to the accompanying drawings in which 1 Figur!v lis an elevation of a portion of a rotary iicld member equipped with my invention; Fig'. 2 is a section through one of the poles, the plane of the section heing parallel to the plane of rotation; Fig. 3 is a section through one of the 'poles at right angles to the plane ot' rotatior1;.Fig. 4 is a viewof one of the antihuntingor damping devices removed ironi the pole Figs. 5 and 6 are sectional views :through a pole equipped with a modified form of my invention, the views he ing similar to Figs. 2 and 3 respectively.

Referring now to the figures of' the drawings, l have shown 10 a portion of a rotary iield member' including a portion of a spider 11 and two field magnets 12 each of which is equipped'with my improved damp? on a. wooden coil seat 16 surrounding the' pole at its base, and is prevented from slipping oil the outer end of the pole hy pole tips 17 of the laminas and aprojecting ledge 18 of each end-plate.

Surrounding the outer end of each pole and hearing against the pole tips 17 and the ledges 1S of the end-plates is a collar or ring 19 of good current conducting material, preierahly of copper, which ring forms a part of the damping or anti-hunting device. As is shown in Fig. 4 the ring is provided with inwardly extending lugs 20 which hear against the sidesof the pole. Intermediate the copper ring and the outermost layer of the coil is an .insulating ring 26. ln addition to the ringacting as a damper it'serves to support the coil.

Extending through the outer end of each pole elose=to the pole face and at right angles to the plane of rotation of the rotary member are a plurality of hars 21 of co per or other good conducting material, in t is case two in number. These bars awith the copper ring 19 compose the damp'ing device of each pole. As is shown therods pass through alined openings 22 and 23 in thelainin and end plates respectively and are secured to the copper rings byscrews 24. in Figs. 2 and 8 the openings in the lamine form partially open slots in the pole face so that the rods are not entirely surrounded by the iron of the laniinae. The openings in the endplates are made slightly larger than the rods, and after the rods are secured together' typeinetal or other easily fusible metal is poured into the openings so as to obtain a firm and compact structure. This, filling metal is shown at 25. As shown in Figs. 2 and 3 the copper rods are surrounded by insulation. This is not necessary however, and may he omitted if desired. The damping bars 21 are preferably -so arranged as to divide the pole face intosections which are whole' multiples of the stator slot pitch, particularly if open stator slots `are emplo 'ed The sections need not be equal in ength and are shown unequal in the drawings. The purpose of this is to insure a uniform area of stator iron in line with each-section at all times so that the flux passing through each section of the pole tace will be constant. Otherwise heavy currents would he genere ated' in the dempers tending to maintain the flux constant when no hunting was taking place.

In Figs. 5 and the construction is substantially the same. In this case however the alined openings 22a in the lamina: do not form open slots in the pole face, and therecesses 2 u in the end-plates to receive the ends of the bars do not extend entirely through said plates, so that after the coil is in' place on the pole, said bars 21 are completely hidden. The bars are secured to the rings 19tL by screws as in the case lirst described, and the excess spaces in the endplates are also filled with metal, such as typemetal.

When the machine is in operation,l the ring and bars, shown best in Iq1 ig. 4 form the seat of induced currents which prevent in a great measure irregularities in speed -above and below synchronism. l Damping or antihunting devices are so well known that further explanation of the theory of operation Dis deemed unnecessary.

It will be seen that by my improved damping or anti-hunting device is very light in weight, simple in construction and easy to manufacture and assemble in the pole. Its construction and arrangement and location in the pole are such ast'o render it moste'l'ective. Furthermore the rods being embedded in the pole, it does not mar the appearance ol a machine to which itis applied as have other damping devices, which heretofore have been more or less cumbersome and bulliy.

l do not wish to be confined to the exact details shown but aim in my ciaims to cover all modifications which come within the spirit and scope of my invention,

What I claim as new and desire to secure by Letters Patent is t. In a dynamo-electric machine, a ield pole made up ol laminary and end plates, and a damping or anti-hunting device therefor, comprising a low resistance ring independent of said laminaa and end plates and surrounding the pole, and one or more separable bars or rods of low resistance embedded in said laminae at right angles thereto and projecting into recesses in said end plates and engaging the ring.

2. In a dynamo-electric machine, a iield magnet comprisingl a pole provided with lateral coil-retaining projecting portions at its outer end and a field coil surrounding said pole, land a damping or anti-hunting device therefor comprising a low resistance ring surrounding said pole and located between the coil and the coil -retaining projecting portions of the pole, a plurality of independent bars or rods of low resistance embedded in the pole face and having their ends extending into said coil-retaining projecting portions adjacent to the ring, and means for fastening the extending ends of said bars or rods to said ring at opposite sides of the pole. 3, In a dynamo-electric machine, a lield Amagnet comprising' a pole-piece and 'lield coil, said pole-piece being made up of a plurality of laniinations and end-plates, a plurality of bars of goed conducting material embedded in the pole face and projecting beyond the laminations, the end-plates being' at their outer ends provided with-coil-retaining' projecting' portions recessed to receive the projecting ends ofsaid bars, a ring ol `goed conducting material surrounding said pole-piece between the coil and the projecting portions ot' the end-plates, and means for fastening' the ring' to the ends ol' said bars, the whole being so constructed that when the pole-piece and coil are assembled the bars are not visible from the exterior.

In testimony whereof' l allix my signature, in the presence oll two witnesses.

ALLAN l. lfll'llll).

IVitnesses: i

Gmo. I5. Sentier, Fano J. Kisser. 

